Deathspell Omega are an avant-garde black metal band from France who are the most well-known band in the Norma Evangelium Diaboli movement. Their lyrical content deals primarily with Satanism on a metaphysical level, and other various theological topics. They are currently two albums through a series of three concept albums which focus on the theological aspects of God, Satan and man's relationship with the two, and are commonly regarded as more thorough lyrically and ideologically than most Satanic black metal bands.

Initially, Deathspell Omega produced raw, traditional black metal akin to Darkthrone's Transilvanian Hunger. However, their 2004 release, Si Monumentum Requires, Circumspice, marked a change to a vastly more experimental (and well-recorded) sound featuring such musical influences as Gregorian Chant and choral music. They have developed a cult following amongst the underground scene since the release of that album, which many consider their seminal work. The first chapter in a planned trilogy, the album was released to critical acclaim and continues to be praised.

The band's work after Si Monumentum Requires, Circumspice has been even more experimental, with the five tracks they released in 2005 - on Kénôse and a pair of splits - totaling nearly eighty minutes in length and actually exceeding the length of Si Monumentum Requires. The second volume of the band's trilogy, Fas - Ite, Maledicti, in Ignem Aeternum, was released on July 16, 2007, outside the United States, and the following day within the United States, to considerable acclaim.

Very little is known about the members of Deathspell Omega, as the band do not have an official website or release information about their membership; however, they have given interviews over the years that explain more about their beliefs and ideology.

Deathspell Omega's assumed members are: Hasjarl, former member of Hirilorn; and Mikko Aspa, responsible for vocals and member of Grunt, Fleshpress, Clandestine Blaze, Nicole 12 and Stabat Mater. Hasjarl allegedly has much to do with the activity of Norma Evangelium Diaboli, and was also involved with EAL. Mikko does Northern Heritage and Freak Animal Records, renowned black metal and power-electronics labels, respectively. Shaxul and Yohann, bandmates of Hasjarl's from Hirilorn, were apparently members of the band at some earlier time, and Encyclopedia Metallum lists former Barbatos member Khaos as a current session bass player.